Food composition



United States Patent FOOD COMPOSITION Ralph W. Kerr, Riverside, and Frank C. Cleveland, Jr.,

Chicago, Ill., assignors to Corn Products Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application November 14, 1956 Serial No. 621,987

Claims. (Cl. 99-139) This invention relates to the preparation of starch phosphate esters wherein the colloidal properties of the starch have been altered primarily by the introduction of distarch phosphate groups, i. e., phosphate cross-linkages, as contrasted to simple monostarch phosphate ester groups. More particularly the invention relates to a process of preparing distarch phosphate esters which retain the granule form of the starch.

Starch phosphate esters which are cross-linked have unusual properties which make them suitable for a number of industrial uses. They are more resistant to gelatinization and pastes made therefrom have increased stability as concerns breakdown by heating compared to untreated starch. In fact, depending upon the degree of cross-linking, starch esters may be prepared which are nongelatinizable in boiling water.

In our copending application, Serial No. 388,914, filed October 28, 1953, there are described and claimed methods for making phosphate esters by heating starch in semidry form with salts of anhydro forms of phosphoric acid, such as metaphosphate, polymetaphosphates, pyrophosphatcs and polyphosphates. After cooling the starch phosphate is washed to remove impurities. Depending upon conditions, several types of products results: (1) monostarch phosphate, (2) distarch phosphates, and (3) monostarch phosphates wherein there is also an appreciable percentage of distarch phosphate groups.

The methods referred to above possess the inherent disadvantage that in order to remove unreacted salts andby-products an extensive washing step after the dry reaction and an additional drying step are necessary. Rewashing and redrying are not only cumbersome operations in starch manufacturing plants but are also relatively costly.

It is an object of this invention to provide a new and novel process for the production of distarch phosphate esters in granule form. Other objects will appear hereinafter.

We have discovered that distarch phosphate in granule form may be produced by heating an aqueous slurry of ungelatinized starch with a water soluble metaphosphate salt at a temperature sufficiently low to maintain the starch in the unswollen granule state, the pH of the system being preferably at least about 9.0.

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The reaction between starch and a metaphosphate salt is understood to proceed as follows:

(Acid sodium pyrophosphate) Under certain conditions, some monostarch phosphate groups may also be produced but, if so, the amount will be negligiblelinking reaction are as follows: In the early stages of the reaction, the paste viscosity of the starch increases significantly. In contrast to simple esterification, however, which also may produce increased paste viscosity, clarity of the cross-linked starch paste does not increase in proportion. Also in contrast to simple esterification, the pastes of cross-linked cereal starches become shorter and more salve-like (or less cohesive). The opposite is true in simple esterification, after which the pastes have higher clarity and longer flow.

As the crosslinking reaction progresses, .viscosity reaches a peak and then declines to very low values; simultaneously shortness and opacity increase (clarity decreases). This is due to a progressive decrease in the ability of starch substance to disperse in water as it becomes progressively more cross-linked. However, in these more advanced stages of cross-linking of starch in granule form, the starch may develop relatively high and stable viscosities if gelatinization conditions are made more strenuous, such as, for example, greatly prolonging the See: Kerr, Chemistry and Industry 0! Starch, 2nd ed-, page 470.

The obvious changes accompanying a starch cross 7 3 cooking time, using autoclave temperatures or adding starch dispersing agents, such as alkali, acid or sugars.

Technically, these are important characteristics in that more rugged starches are produced which are stabilized to break down by conditions employed by those who use the starch. For example, the relatively tender waxy starches, such as waxy maize, or the non-cereal starches, such as tapioca, which rapidly deteriorate on cooking in many uses to a thin, slimy paste, may be stabilized by the correct amount of cross-linking so that they actually increase in viscosity as cooking time is extended. Moreover, the cohesiveness of these gels is reduced to a more palatable texture. The same may be said for certain derivatives of the cereal starches, such as corn monostarch phosphates (likes the potato and tapioca starches they so strongly resemble). They also tend to deteriorate on prolonged cooking or at autoclave temperatures or under other adverse conditions more readily than untreated cereal starch. A definite amount of cross-linking converts corn monostarch phosphate into a product quite similar to a cross-linked Waxy starch. This is an important development in that some of the undesirable characteristics of starches, such as corn starch, can be changed to desirable characteristics. Finally, in the last stages of cross-linking, the starch becomes insolubilized. Starch in the granule state containing a suflicient number of distarchphosphate groups will not gelatinize even when boiled in water. Such a product may be used as an inert dusting powder, unaffected by moisture or temperature, such as is used in steam sterilization. The product may, accordingly, be used for dusting and lubrication of surgeons gloves which may be sterilized in the autoclave and the starch will not lose its lubricating or de-tackifying efiect.

The process of the present invention is simple and accordingly can be carried out with no difiiculty. A slurry of ungelatinized starch in water containing the requisite amount of metaphosphate and having a suitable pH is heated with agitation at a temperature sufiiciently low to maintain the starch in the unswollen granule state. In general temperatures between 40 C. and 50 C. are satisfactory, but higher or lower temperatures may be used depending on alkalinity and whether a gelatiniza tion inhibitor is used. After the reaction has proceeded to the desired degree, the resultant distarch phosphate is filtered, washed, the pH adjusted and the product dried.

The invention is applicable to all varieties of raw starch, e. g., corn, tapioca, wheat, waxy sorghum, grain sorghum and the like. Further, the invention is applicable to various modified starches and derivatives of starch, e. g., thin boiling starches, oxidized starches, starch ethers, starch esters and the like. The term starchj as used in the claims, is intended to include all of the above listed substances.

As previously mentioned, the phosphorylating agents are the water soluble metaphosphates and polymetaphosphates and of these sodium nimetaphosphate is the preferred reagent. Although some commercial samples of other phosphates, e. g., sodium tripolyphosphate produced an appreciable degree of esterification of starch in aqueous slurry, others did not, and it is thought that metaphosphate impurities were responsible for the esterification in the former case.. The pyrophosphates appear to give very little, if any, reaction with starch in the wet state.

The phosphorylation of starch in accordance with the present invention proceeds more efficiently at a high pH, preferably at 11.0 or above although a pH of about 9.0 is satisfactory. Various alkaline materials, e. g., sodium hydroxide, sodium carbonate, lime, and the like may be used to make the pH adjustment.

The amount of metaphosphate required to produce cross-linking suificient to show an increase in the viscosity of starch is quite small, i. e., of the order of about 0.03 percent-, b ased on the dry weight of the starch, when the time of the reaction is one hour, the temperature 50 C.,

and the pH 11. Under these same conditions of time, temperature and pH, about 0.6 percent of metaphosphate will make the starch nongelatinizable in boiling water. Although amounts higher than about 0.6 percent are not detrimental for these conditions, such amounts serve no useful purpose. creased temperature, and pH, and with increased amount of metaphosphate up to the point where the starch becomes nongelatinizable. If temperatures below 50 C. are used, it is obvious that correspondingly more metaphosphate should be used if time and pH are the same. A practical operating range of metaphosphate is about 0.01 to about 3 percent.

It has been found that the concentration of sodium added as a sodium salt has an efiFect on the degree of phosphorylation, the higher the concentration (within practical limits) the higher the degree of phosphorylation. A total sodium ion concentration of about 0.4 mole per liter gives satisfactory results.

The following examples, which are intended as typical and informative and in no way limiting the invention, will further illustrate the invention.

EXAMPLE 1 Production of high viscosity, partially cross-linked corn One mole of. corn starch-( grams at 10 percent moisture content) was suspended in 325 m1. of water into which had been dissolved 3.3 grams of commercial sodium trimetaphosphate (Victo'rChe nical Company) and suiiicient sodium carbonate butter 5.45 grams) to adjust the pH of the starch slurry to 10.2. The slurry was heated to 50 C. with stirring and held at this reaction temperature. Samples were removedatintervals shown in Table I, filtered, washed and adjusted to pH 6.7 with hydrochloric acid and dried. I p

Scott viscosity tests were made on these samples in accordance with procedures described in Kerr, Chemistry and Industry of. Starch, 2nd edition, pp 119-121. Results were as follows: i

TABLE I Scott: Viscosity, Sec/50 ml.

Reaction Time, Min.

Unless otherwisespecified, viscosity tests were run using 15 grams of starch at 12 percent moisture content in 280ml. water.

The viscosity of the heat gelatinize'd samples increased to a maximum in about 50 minutes reaction time and then decreased as the cross-linking reaction continued. A sample taken from the reaction mixture after 24 hours would not gelatinize when boiled in water.

The high viscosity sample taken after 50 minutes reaction time formed a paste which was more opaque and less cohesive than untfeated corn starch and by analysis had a phosphorus content of 0.03 percent. This starch when made into adhesive formulations suitable for pasting paper products, such' ,as paper bags or corrugated paper board, gave higher bodied pastes which permitted the use of greater dilutions than 'l lfi t'r cttbd earn starch;

The reaction proceeds faster with in-- and agitation better than untreated corn starch.

EXAMPLE 2 Procedures given in Example 1 were repeated with the exception that only one gram of sodium trimetaphosphate was used per 180 grams of corn starch (at percent moisture content) and 6.65 grams of sodium carbonate was added.

Samples were removed at time intervals shown in Table II, washed, neutralized and dried. Paste clarity of pastes made from these samples was determined as follows: A slurry of the starch product in water is adjusted to pH 6.5 and at about 1 percent concentration. The flask is then immersed in boiling water for 30 minutes with occasional stirring, then cooled to 25 C. and adjusted in volume so as to contain 1 gram starch per 100 ml. At 25 C., the paste is introduced into a 13 mm. cell of a Coleman spectrophotometer, the light wave adjusted to 7r=650 ma and the percent light transmission determined, using distilled water as reference for 100 percent light transmission.

TABLE II [Reaction of sodium trimetaphosphate with corn starch (one gram/180 grams) in aqueous slurry at pH 10.2 and 50 0.]

Again it will be observed that the Scott viscosity of the products increased to a maximum and then declined. Clarity of pastes, in general, declined as cross-llnkmg progressed. The effect of lower concentration of sodium trimetaphosphate under these conditions was to retard the esterification so that now the peak viscosity starch phosphate was not obtained until approximately 80 minutes reaction time.

EXAMPLE 3 The efiect of lower trimetaphosphate concentration in aqueous starch slurries at the higher pH value oil] and at 50 C.

Even still lower trimetaphosphate concentrations than used in Examples 1 and 2 were found to be effective in producing all degrees of cross-linking in corn starch. However, the reaction was accelerated by using the higher pH value of 11 in this experiment.

One molar weight of corn starch was stirred into 220 ml. of water into which had been dissolved 4.52 grams of sodium carbonate and the amounts of sodium trimetaphosphate shown in Table 111. Just prior to adding the starch, 4 ml. of 10 N sodium hydroxide was stirred into the reaction solution. The pH value of the slurry was 11. The reaction mixture was held at 50 C. for one hour then cooled to room temperature, adjusted to pH 6.5 with bydrochloric acid, washed and dried. A series of such reactions was run using varying amounts of sodium trimetaphosphate between 0.05 and 1.0 grams. The Scott viscosities of these products are shown in Table III.

. the seconds noted for 50 revolutions.

TABLE III [Efiect of lower trimetaphosphate concentrations on aqueous slurries of starch at pH 11 (50 C. for one hour) Stormer Test, Sec./ 50 rev.

Scott Viscosity, See/50 m1.

0 (untreated) PPPPPPPCQ It will be observed from the results in Table III that at pH 11 and 50 C. as little as 0.15 gram of sodium trimetaphosphate per 180 grams corn starch at 10 percent moisture content produced a peak Scott viscosity starch product within one hour by the aqueous slurry method.

Under these conditions also, as little as 0.75 to 1.0 gram of sodium trimetaphosphate produced a starch product so completely cross-linked that when it was held in boiling water bath for 15 minutes, it had no Scott viscosity that could not be accounted for by 15 grams of unswollen starch granules in 280 m1. of water. Water alone gives a Scott viscosity of 11 seconds.

This example illustrates additionally the higher reaction rate at pH 11 than was obtained at pH 10.2 in Examples 1 and 2.

Pastes of several of the products used for Scott viscosity were cooled to 25 C. and after one hour at this temerature were placed in the cup of a Stormer viscometer. A gram weight was used to actuate the spindle and As indicated in Table III pastes made from untreated corn starch set to a rigid gel atfer one hour and pastes from starch treated with 0.05 and 0.10 gram of trimetaphosphate, were too thick to measure by this test. The peak Scott test starch however was fluid, although quite thick and relatively short in body. As the concentration of trimetaphosphate used was increased, cold paste body at one hour decreased until finally only a watery suspension was obtained. As the extent of cross-linking was increased, the cold pastes became increasingly less cohesive and salve-like.

EXAMPLE 4 Eflect of added cation on the reaction between trimetaphosphate and starch in aqueous slurry The equation given for this reaction between starch and trimetaphosphate indicates that acid groups (acid sodium pyrophosphate) are produced during the reaction. Since the reaction proceeds more readily at higher pH values, one function of the added carbonate in Examples 1 to 3 is to act as buffer. However, the added sodium also appears to act beneficially on the phosphorylation as well. If sufiicient alkali is added to maintain a high pH value, then on a molar basis sodium in NaCl is as effective as in Na CO Three reaction mixtures were set up as follows: 180 grams of corn starch (at 10 percent moisture content) was stirred in 320 ml. of water into which had been dissolved one gram of sodium trimetaphosphate and 4 ml. of 10 N NaOH. To one, 4.52 grams of Na CO was also included and to a second, 5 grams of NaCl had been added; the third contained no further additions. All three were stirred for 2 hours at 50 C., then cooled, neutralized with HCl, washed with water and dried.

Data on these products are shown in Table IV.

TABLE IV der the trademarks Biosorb and vulva-100," as non 17 [Effect of sodium concentration on the reaction between starch and aelatlmzmg products were tested m companson' trimeta phosphate.]

TABLE V Additions of Sodium in MolesXl /1O0 Total m1. trom- Sodium pH Value Gelatiniza- Concen- Scott Stormer Percent of Heated tion Test, tration Vis., est, Sample Calcium Aqueous ml. of inMoles See/50 Sea/50 Phosphate Suspension Starch (NaPO NaOH NaGl NazGO X ml. rev. Sediment Per 100 Example G-A 0 7. 1 19 Example 643 0. 25 7. 2 22 2. 9 11.7 25.0 39. 6 13 3. 5 Vilma-100 20 2.9 11.7 25.0 39.6 12 3:0 Biosorb a2 2.9 11. 7 14. 6 120 850 Untreated Corn Starch 100 In all cases during these reactions, the alkalinity was within the range pH 11.2 to 11.6. Actually, the pH value of the reaction mixture containing only NaOH and the trimetaphosph'ate was slightly higher than the others. Nevertheless, at the end of 2 hours, the crosslinking reaction in this case had only advanced to the region of a super-viscosity starch whereas with either sodium carbonate or sodium chloride added, the crosslinking reaction had proceeded to the stage where the starch was substantially ungelatinized by the Scott viscosity cooking procedure.

EXAMPLE 5 Use of lime as catalyst instead of sodium hydroxide and carbonate to produce a peak Scott viscosity corn starch diphosphate EXAMPLE 6 Production of a non-gelatinizable, mobile dusting powder 1100 grams of corn starch was stirred into 1300 m1. of water into which had been dissolved 33 grams of sodium trimctaphosphate, 30 grams of sodium carbonate, and 11 grams of sodium hydroxide. The pH value was 11.2. This slurry was stirred at 50 C. for 24 hours.

At the end of this time, the slurry was cooled to room temperature and a portion (part A) was removed, adjusted to pH 6.5 with hydrochloric acid, thoroughly washed in water and dried.

During purification of the balance (part B) of the reaction mixture sufiicient calcium chloride was added so that when washing of the product was terminated and the product dried, the starch powder contained an amount of calcium equivalent to 0.25 percent calcium phosphate.

This dry starch powder was found to be very mobile and useable as a dusting powder, particularly as a surgical rubber dusting powder, because of its great resistance to gelatinization as shown below; surgical rubber gloves are sterilized before use by steam autoclaving and accordingly any dusting powder used on the gloves must withstand steam sterilization.

Both starch products made in this example were treated as follows: 5 grams of product was stirred into 100 ml. of water and heated in a boiling water bath for minutes. The heated mixture was adjusted to 100 ml. in volume and poured into a 100 ml. graduated cylinder. After 24 hours at room temperature, it was noted that substantially all of the starch had settled out. The volume of sedimented starch was noted and is shown below. Two other commercial starch products sold un- EXAMPLE' 7 Efiect of pH value-on the reaction of starch inaqucous slurry with sodium trimetaphosphate [Reaction of aqueous slurries of corn starch with sodium trimetaphosphoto at 50 0. and at pH values of 8. 9, 10 and 11.]

ucts from Reactions at pH Values Reaction Time, Min.

P 8 pH 10 pH 11 1; (untreated) The results show the great retardation in rate of crosslinking by trimetaphosphate when the pH value is lowcred over the range from 11 to 8. Whereas at pH 11, the peak viscosity occurred within the first 5 minutes, at pH 10 the time was about minutes, for pH 9 sometime after minutes and at pH 8 sometime after 24 hours. Extensive cross-linking (Scott values less than 20) requires less than 2 hours at pH 11, 5 hours at pH 10, about 48 hours at pH 9 and may not occur at all at pH 8, since the reagent is hydrolyzed within several days at this temperature and pH 8.

EXAMPLE 8 Production of partially cross-linked waxy sorghum starch with trimetaphosphate in aqueous slurry at pH 10.2; stabilized waxy starch 350 grams of waxy grain sorghum starch was stirred into 648 ml. of water into which had been dissolved 2 grams of sodium trimctaphosphate and 13.3 grams of sodium carbonate. The pH of this slurry was 10.2. The

slurry was stirred at 50 C. and samples were removed Scott Viscosity Values Of Prod- TABLE VII [Reaction of aqueous slurries of waxy grain sorghum starch with trimetaphosphate at pH 10.2 and 50 0.]

I In these tests only 12 grams of starch product was used in 280 ml. of water.

Again a cross-linking reaction is indicated by the results that as the reaction progressed the Scott viscosity increased to a maximum and then rapidly decreased. Progressively with this change, the cohesive nature of cooked and cooled waxy starch became less.

The product made at 75 minutes reaction time, that is, with a degree of cross-linking considerably more than enough to bring the starch product to a peak viscosity, is a type of stabilized Waxy starch product of considerable technical importance. When untreated waxy sorghum or waxy maize starch is gelatinized in water at the boiling point the viscosity increases rapidly to a very high value and then progressively decreases to very low value. Cold pastes are long and slimy and as cooking progresses, they become relatively thin in consistency. The deterioration in viscosity of waxy starch on cooking is accentuated by the presence of acids and sugars. Therefore, although waxy starches have inherently the properties of giving pastes of high clarity and freedom from set back to irreversible gels, they are not acceptable as thickening agents in many application, such as, for example, making of fruit pies, production of gum confections, such as gum drops or orange slices, and the canning of cream style corn. However, the waxy starch with a degree of cross-linking as represented by the sample produced in 75 minutes reaction time, is eminently suited for use as a thickening agent for applications above enumerated as well as many others because of the stabilization of viscosity effected by the phosphate cross-linking. As the starch product is cooked, the viscosity rapidly approaches a useable value and thereafter the viscosity remains relatively constant. Even when cooked in the presence of acids, such as citric, or sugars, or cooked under pressure, the pastes show a remarkable stability. As these pastes are cooled, they remain fluid and of acceptable body and moreover, the texture is very much less cohesive and slimy than untreated waxy starch pastes.

EXAMPLE 9 Stabilizing corn monostarch phosphate by treatment in aqueous slurry with trimetaphosphate Corn starch was esterified in a. semidry reaction with sodium tripolyphosphate, in accordance with the method described in copending application, Serial No. 388,914, filed October 28, 1953, as follows: One molar weight of corn starch (180 grams at 10 percent moisture) was stirred into 215 ml. of water into which had been dissolved 15.5 grams of sodium tripolyphosphate. The pH was approximately 8.5. The starch was filtered by suction to form a cake of approximately 45 percent moisture content. This was dried at 60 C. to approximately 12 percent moisture content. By analysis, 9 grams of the polyphosphate (0.08 mole calculated as a sodium monophosphate) was retained by the starch, the balance being in the aqueous filtrate.

This starch was now heated with stirring, and with 10 provision for moisture removal, at temperatures between C. and C. and then cooled. The starch product suspended in 250 ml. or? water, now showed a pH of 7.0. It was filtered and washed twice more by suspension in 250 ml. of water followed by filtration with suction. The starch was then dried to a commercial moisture content of approximately 10 percent for a powdered starch.

The product contained 0.37 percent phosphorus, equivalent to a starch phosphate ester with a D. S. of 0.03 as orthophosphate groups. The starch when gelatinized by heating in water formed a very viscous sol (as indicated by Scott viscosity value) with little or no tendency to gel or increase in viscosity with age (as indicated by Stormer consistency values). The sol had very high clarity compared to untreated corn starch (both measured at pH 6.5) and had long flow characteristics similar to tuber or waxy starches.

The monostarch phosphate thus obtained was treated in an aqueous slurry with sodium trimetaphosphate by procedures the same as used in Example 8. A product was obtained with stabilized paste properties quite similar to the 75 minute reaction product of the waxy sorghum starch of Example 8; the untreated monostarch phosphate showed unstable paste properties similar to untreated waxy sorghum starch.

EXAMPLE 10 Stabilizing hydroxyethyl corn starch ether by treatment in aqueous slurry with trimetaphosphate A commercial sample of hydroxyethyl corn starch of low D. S. (0.05) and in the granule state was stabilized by introducing phosphate cross-linkages as follows: 162 grams (dry basis) of the starch ether was stirred into 324 ml. of water into which had been dissolved one gram of sodium trimetaphosphate and 6.66 grams of sodium carbonate. The pH value of the slurry was 10.2. The slurry was heated at 50 C. and samples were removed at time intervals, as shown below. These samples were cooled to room temperature, adjusted to pH 6.5 with hydrochloric acid, filtered, washed in water and dried.

Scott viscosities and Stormer consistency values were determined using 13 grams of product (at 12 percent moisture content) in 280 ml. of water.

TABLE VIII Stormer Consistency, Scott See/50 Revolutions Reaction Time, Min. Viscosity,

Sec/50 ml.

1 hr. at 24 hrs. at

Peak viscosity was reached between 0 and 30 minutes but was not measured.

It will be observed that as cross-linking progressed, the product showed progressively less tendency to thicken up when pasted, cooled and aged. Moreover, the ether which had been cross-linked by trimetaphosphate treatment (for example, the product at 120 minutes) was more stable at elevated temperatures and formed a less slimy paste when cold. The latter change in character is desirable in many applications for applying adhesives and sizes made from modified starches.

EXAMPLE 11 Stabilizing an oxidized thin boiling corn starch by treatment in aqueous slurry with sodium trimetaphosphate A commercial sample of a thin boiling starch made by oxidizing corn starch in the granule state with alkaline sodium hypochlorite was treated as follows: grams grams of sodium trimetaphosphate, 4.52 grams of sodium carbonate and suflicient sodium hydroxide to adjust the final slurry to pH 11. The starch slurry was stirred and heated at 50 C. for 90 minutes. The slurry was cooled and filtered and the starch, still in the granule state, was washed in water, neutralized with hydrochloric acid, filtered and dried.

Scott viscosity was determined using 28.35 grams of starch in 280 ml. of Water and found to be 102 seconds per 100 ml. A duplicate viscosity determination was run with the exception that the paste was held in a boiling water bath for 90 minutes instead of the 15 minutes, used in the Scott test. The viscosity was now 72 seconds per 100 ml. An otherwise untreated, oxidized corn starch commonly used in textile sizing operations was tested similarly. The Scott test (28.25'g, in 280 ml.) was 108 after the usual 15 minutes pasting period. Heated for 90 minutes in aboiling water bath, however, the viscosity was now only 32 seconds. Thus the untreated oxidized starch had lost about 70 percent of its viscosity on being held for 75 minutes in the vicinity of holding temperatures usedin textile mills for sizes, such as, for example, warp sizes. This loss amounts to almost 1 percent per minute and is highly objectionable from a textile sizing operation standpoint. The stabilized, oxidized starch of this example, however, lost only 29.4 percent of its viscosity during a comparable period. Moreover, the paste of the stabilized starch set back, or jelled, less on cooling and standing, an added advantage in mills where left over size isheld from one days operation to the next.

EXAMPLE 12 Crossdinking com starch with sodium metaphosphate A sample of commercial sodium metaphosphate was found to be partially insoluble in water. About 60 percent of the sample dissolved. The dissolved portion which contained one gram of dry solids was included in the 324 ml. of make-up water in which 180 grams of corn starch was suspended. 6.66 grams of N21 CO was added and the final pH value of the starch slurry was 10.2. The slurry was stirred at 50 C., and periodically samples were removed, adjusted to pH 6.5 with HCl, filtered, washed in water and dried. Scott viscosities of these products are shown in Table IX.

TABLE IX [Reaction of sodium metaphosphate with corn starch (one gram/180 grams) in aqueous slurry at pH 10.2 and 50 0.]

Clarity of 1% Pastes as Percent Light Transmission at )\=650 m Scott Viscosity, See/50 ml.

Reaction Time, Min.

(untreated) 45.

EXAMPLE 1 3 CrossJinking corn starch with sodium hexametaphosphate Corn starch was made intoa slurry with a percent aqueous solution of sodium hexametaphosphate that contained sufiicient sodium hydroxide to give a pH value of 11.1 to the final reaction mixture. The aqueous suspension had a density corresponding to 22 B. at 30 C. The reaction mixture was stirred at 50 C. for 24 hours then cooled, adjusted from pH 11.0 to 6.5 with hydrochloric acid, filtered, thoroughly washed anddried.

The dried product when resuspended in water and heated for 15 minutes in a boiling water bath as in running the Scott viscosity by determination remained substantially ungelatinized.

EXAMPLE 14 Use of distarch phosphate in cherry pie fillings Drained cherries (frozen and thawed) (5 parts cherries +1 part sucrose), total lbs 64 Cherry juice (5 parts juice +1 part sucrose),

total lbs 21 Sucrose lbs 8 Corn sirup lbs 4 Artificial color oz 0.15

The mix was stirred slowly while cooking to 190 F. At this time the distarch phosphate slurry was added and the temperature was raised to and held at 196 F. for 10 minutes.

Thereupon the hot prepared pie fillings were poured into cans and sealed. The cans were then immersed in boiling water for 10 minutes and cooled to room temperature.

Cherry pie fillings were similarly prepared using untreated waxy sorghum starch.

At periodical intervals, over several weeks time, cans of each of the tWo pie fillings were opened. Fillings made containing the distarch phosphate remained fluid but of satisfactory consistency and the liquid portion was clear. Fillings made of untreated waxy starch were unacceptably fluid as made, and after about two days, were of a Watery consistency.

Cherry pies were made and baked from both types of fillings. The cherry pie fillings made from the distarch phosphate were fluid, of a very desirable consistency, clear and of a very attractive appearance. Those made from untreated waxy sorghum starch were unacceptably thin bodied so that much of the juice ran out of the pie. In comparison, fillings similarly made and used, employing untreated corn starch were opaque, whitish in appearance and gel-like in consistency.

EXAMPLE 15 Use of distarch phosphate in cream style corn In canning sweet corn (cream style), field tests have shown that distarch phosphate prepared in accordance with Example 9 gave the same consistency to cream style corn as twice the Weight of untreated corn starch. Moreover, the consistency was smoother with distarch phosphate since it was superior in preventing curdling of the sweet corn protein during the cooking and canning operation.

EXAMPLE 16 This example also shows the applicability of dist'arch phosphate in fruit fillings for pics.

Canned, sour, pitted cherries were drained to separate the juice from the meats. liters of juice were diluted with '70 liters. of water andwhile heating to about95 C., 100 kilos of sugar was dissolved in the liquor. To the heated solution was now added 74 kilos of distarch phosphate (75 minute sample of Example 8) which had been slurried in 70 liters of water. Heating was continued until the starch had gelatinized after which 192 kilos of drained cherry meats plus 70 kilos of sugar were stirred into the cooked mixture.

Pie crusts were then filled with the mixture prepared above and the pies were baked at 400 F. for approximately 30 to 35 minutes.

The pics were inspected after cooling to room temperature for 3 hours and again at the end of 24 hours.

For comparison, a batch of pies was made with corn starch and another batch with waxy sorghum starch using the proportions and procedure above given.

After 3 hours cooling to room temperature, the pies containing the distarch phosphate were of clear, slightly fluid consistency, and accordingly presented a very appetizing appearance; the pies containing corn starch were slightly thinner and more opaque while the pies containing the waxy sorghum starch, although extremely clear, were so thin the filling had soaked badly into the lower crust and had boiled over the upper crust.

After 24 hours storage, the pies containing the distarch phosphate presented substantially the same appearance as at the end of 3 hours; the pies containing corn starch had set up to an immobile, opaque gel while those containing waxy sorghum starch were extremely thin.

For commercial bakeries, where pies do not reach the ultimate consumer until many hours, perhaps a day or more, after baking, the advantage of using distarch phosphate to prepare a stable, clear, fruit filling is obvious.

EXAMPLE 17 This example shows among other things the stability of our distarch phosphates when used under conditions involving freezing and thawing.

Procedures given in the previous Example 16 for preparing fruit pie filling were repeated. However, after the fillings were placed in pie crusts, they were frozen and held at a temperature of 17.7 C. F.) for 3 days while wrapped in a metal foil container to prevent moisture loss, then thawed and baked as in the preceding example.

Pies made with the distarch phosphate presented the same appearance as freshly made and baked pies formulated with this starch. Pies made with corn starch were a solid mass of opaque retrograded gel from which some thin watery liquid had synerized during thawing and baking to soak the crust. Pies containing waxy sorghum starch were exceedingly thin, both as baked and after aging, so that much of the filling had soaked into and overfiowed the crust.

During recent years a merchandising innovation has been attempted by pie makers wherein unbaked, or partially baked, pics are frozen and distributed in the frozen state to retail stores where they are purchased by the ultimate consumer. The latter then thaws the pie and completes the baking. The disadvantage to this phase of frozen food manufacture has been heretofore that the commonly available starches used as pie filling thickeners have not been stable to the freeze thaw operation, or have been unstable in the presence of fruit acids and sugar, or both, and unacceptable products have resulted. The developent of a distarch phosphate for use as thickening agent in frozen pies and which would be stable under the conditions imposed is, therefore, a significant advancement in the art.

Our distarch phosphates have been found to be equally stable when used in other frozen food preparations, e. g., gravy, meat sauces.

EXAMPLE 1 8 This example together with previous examples and the one to follow shows the breadth of our invention in respect of use of distarch phosphate in products containing fruit and other acids, e. g., fruit fillings and fruit puddings.

A product made in accordance with the procedure of Example 9 having the following characteristics was used:

(1) D. S. of about 0.02 as monostarch phosphate, 1. e., an average of 2 monophosphate ester groups per anhydro glucopyranose groups.

(2) Scott viscosity 50-100 seconds per 50 ml. using 3 grams of 12 percent moisture distarch phosphate per 280 ml. of water.

(3) Clarity of a 1 percent paste about 50 to 65 percent.

This product was used in making a fruit pudding from cherries, in accordance with the method described in Example 14, using the same ratio of ingredients except the amount of distarch phosphate used corresponded to 4 lbs.

The resultant fruit pudding was superior to a pudding made from the same ratio of untreated corn starch in the following respects: The pudding containing the distarch phosphate was very clear, had good body and a relatively short texture consistency which gave a very pleasant taste and mouth feel. Moreover, the characteristics remained substantially unchanged when the pudding was aged for 24 hours. The pudding made from the untreated corn starch was of unacceptably thin consistency as first made and cooled. After 24 hours this pudding became an opaque, off-colored gel which masked the fruit and presented an unappetizing appearance and unpleasant taste.

EXAMPLE 19 An hydroxyethyl grain sorghum distarch phosphate made, in accordance with Example 10, was used in a fruit pudding. The distarch phosphate had the following characteristics:

(1) D. S. of about 0.04 as hydroxyethyl groups, i. e., an average of 4 hydroxyethyl groups per 100 anyhdro glucopyranose groups.

(2) Scott paste viscosity 30 to 50 seconds per 100 ml., using 10 grams of 12 percent moisture diphosphate starch in 280 ml. of water. 1

(3) Clarity of a 1 percent paste about 18 to 25 percent.

This product was used in making a fruit pudding from cherries, in accordance with the method described in Example 14, using the same ratio of ingredients except the amount of distarch phosphate corresponded to 4 lbs.

The resultant fruit pudding was superior to a pudding made from untreated hydroxyethyl corn starch in the following respects: The fruit pudding made with the hydroxyethyl grain sorghum distarch phosphate was very clear, heavy bodied, and had a relatively short textured consistency which gave a very pleasing taste and mouth feel. Moreover, the characteristics remained substantially constant when the pudding was aged 24 hours. On the other hand, a fruit pudding made with the same ratio of all ingredients, but substituting a 0.04 D. S; hydroxyethyl corn starch for the distarch phosphate derivative of the same hydroxyethyl corn starch, was unacceptably fluid in body and had a long, viscous, or glue-like consistency, which gave an unpleasant, slimy mouth feel.

EXAMPLE 20 Drained peaches oz 50 Water oz 12 Cane sugar oz 8 Citric acid grams 5 Waxy sorghum distarch phosphate do 54 Waxy sorghum starch do 6 The starch was slur'ried in part of the water. The rest of'the ingredients were heated to 190 F. andthe starch slurry added and the mix was heated at 196 F. for 10 minutes. Pie crusts were filled with the mix.

A second pie was prepared in identical manner with the exception that 60 grams of waxy sorghum starch was used as the sole thickening agent.

Both pies were baked in an oven at 400 F. for 30 minutes and were allowed to cool to room temperature. They were inspected 3 hours after baking and again after 24 hours.

The pie filling containing the waxy sorghum distarch phosphate was very clear, had good body and the gelatinized thickening liquor clung wellto the fruit particles; it had not overfiowed the upper crust nor soaked into the lower crust. The appearance of the filling was the same at 24 hours age as at 3 hours.

The filling containing only the waxy sorghum starch as thickening agent was unacceptably thin-bodied, both at 3 hours age and at 24 hours age. The filling liquor had not held to the fruit and had overfiowed the upper crust and had soaked into the lower crust.

EXAMPLE 21 This example shows the use of waxy sorghum distarch phosphate having a viscosity of 50 seconds in raw fruit pie fillings. The viscosity was measured by Scott test in the manner indicated in Example 7. The formulations I Made at a ratio of 1 1b. of starch to 2.3 lbs. of water.. Starch consists of 90 percent waxy sorghum distarch phosphate and 10 percent waxy sorghum starch.

All of the ingredients listed above except the starch slurry were heated to 90 C. and then the starch slurry was added and the mix cooked at 90 C. for minutes. The resultant liquor was poured over the fresh fruit and pies were baked in conventional manner.

The baked pies were inspected at various intervals of times after cooling to room temperature. In all cases, the fruit pies which contained the distarch phosphate had a clear, slightly mobile filling of about the same consistency after 24 hours as when freshly baked. In all cases the filling clung well to the fruit meats.

In control tests wherein corresponding amounts of all waxy sorghum starch was used in the production of peach, blueberry, apple and cherry pics, the fillings were thin, soaking into the lower crust and boiling over the upper crust, and remained thin in consistency even 24 hours after baking.

The percent addition of untreated waxy sorghum starch was made with the 90 percent distarch phosphate so as to give body quickly to the filling within the short period of precooking at 90 C. The distarch phosphate does not develop its full body until after longer cooking times, or when higher temperatures are used, such as are encountered, for example, in the actual baking of the ples.

The addition of a minor proportion, e. g. about 10 percent, of readily gelatinizing waxy starch to distarch phosphates, has also been founddesirable in certain specific commercial canning processes producing canned, fruit pie fillings, wherein the time or temperature used in the precooking step is not sutficient to develop a body 16 to the liquor so as to hold the fruit meats uniformly suspended until the cans are filled, which are then subjected to a pressure cooking operation.

This application is a continuation-in-part of application Serial No. 448,359, filed August 6, 1954.

We claim:

1. A cooked fruit filling for pics and the like with improved stability against thinning and retrogradation comprising fruit, sugar and a distarch phosphate as a thickening agent; said distarch phosphate being insoluble in cold water and gelatinizable in hot water and being made by treating unswollen granule starch in aqueous slurry with a water soluble salt from the group consisting of metaphosphates and polymetaphosphates in the amount of at least about 0.01. percent, based on the dry weight of the starch, at a temperature sufliciently low to maintain the starch in unswollen granule state, and for a time to effect the desired degree of esterification, the pH of the system being maintained at at least about 9.0, thereafter neutralizing the system and washing with water and drying the resultant distarch phosphate.

2. A cooked fruit filling for pies and the like with improved stability against thinning and retrogradation comprising fruit, sugar and, as a thickening agent, a distarch phosphate being insoluble in cold water and gelatinizable in hot water and made by treating unswollen granule starch in aqueous slurry with sodium trimetaphosphate in the amount of at least about 0.01 percent, based on the dry weight of the starch, at a temperature sufiiciently low to maintain the starch in unswollen. granule state for a time to effect the desired degree of esterification, the pH of the system being maintained at at least about 9.0 and the sodium ion concentrationat at least about 0.4 mole per liter during esterification, and thereafter neutralizing the system and washing the resultant distarch phosphate with water.

3. A cooked fruit filling for pies and the like with improved stability against thinning and retrogradation comprising fruit, sugar and, as a thickening agent, a corn distarch phosphate being insoluble in cold water and gelatinizable in hot water and made by treating unswollen granule corn monostarch phosphate in aqueous slurry with a water soluble salt from the group consisting of metaphosphates and polymetaphosphates at a temperature sufiiciently low to maintain the monostarch phosphate in the unswollen granule state for a time to effect the desired degree of esterification, the pH of the system being maintained at at least about 9.0 and the amount of salt being at least about 0.01 percent, based on the dry weight of the monostarch phosphate.

4. A cooked fruit filling for pies and the like comprisingtruit, sugar and, as a thickening agent, a waxy grain distarch phosphate made by treating unswollen granule waxy grain starch in aqueous slurry with a water soluble salt from the group consisting of metaphosphates and polymetaphosphates in the amount of at least about 0.01 percent, based on the dry weight of the starch at a temperature sufficiently low to maintain the starch in unswollen granule state until the Scott viscosity of a paste is reduced from about 160 to about 40 to seconds per 50 ml., using 12 grams of starch product in 280 ml. of water and the clarity of a one percent paste is reduced to about 15 percent of the light transmission of Water, the pH of the system being maintained at at least about 9.0, thereafter neutralizing the system and washing with water and drying the resultant distarch phosphate.

5. A cooked fruit filling for pies and the like comprising fruit, sugar, citric acid and, as a thickening agent, hydroxyethyl grain sorghum distarch phosphate having a D. S. in respect to hydroxyethyl of about 0.04 and a 7 Scott paste viscosity of 30 to 50 seconds per 10 ml., using duced to about 18 to 25 percent of the light transmission of water, said distarch phosphate being made by treating unswollen granule hydroxyethyl grain sorghum starch in aqueous slurry with a water soluble salt from the group consisting of metaphosphates and polymetaphosphates in the amount of at least about 0.01 percent, based on the dry weight of the starch, at a temperature sufficiently low to maintain the starch in unswollen granule state until the aforementioned viscosity of a paste is obtained.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Switzerland May 8, 1913 UNITED STATES PATENT oTTTcE CERTIFICATE 6F CG EQHUN Patent No, 2,852,393 September 16, 1958 It is herebjr certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 15, for "likes" read me like 001mm 6 line Al, for "atfer read after column 7, Table IV, in the heading of the first four columns, and in the heading of the fifth column, for "10 each. occurr nce, read 10 3 column 9, line 4% for "application" read applioations column 13 line 6% for "developent" read develop ment column 16, line 72, for "16 ml" read 100 ml e Signed. and sealed this 6th day of January 195% SEAL) ttest:

KARL HQ. AXLINE ROBERT GWATSON Attesting Ofiicer Commissioner of Patents' 

1. A COOKED FRUIT FILLING FOR PIES AND THE LIKE WITH IMPROVED STABILITY AGAINST THINNING AND RETROGRADATION COMPRISING FRUIT, SUGAR A DISTARCH PHOSPHATE AS A THICKENING AGENT; SAID DISTARCH PHOSPHATE BEING INSOLUBLE IN COLD WATER AND GELATINIZABLE IN HOT WATER AND BEING MADE BY TREATING UNSWOLLEN GRANULE STARCH IN AQUEOUS SLURRY WITH A WATER SOLUBLE SALT FROM THE GROUP CONSISTING OF METAPHOSPHATES AND POLYMETAPHOSPHATES IN THE AMOUNT OF AT LEAST ABOUT 0.01 PERCENT, BASED ON THE DRY WEIGHT OF TE STARCH, AT A TEMPERTURE SUFFICIENTLY LOW TO MAINTAIN THE STARCH IN UNSWOLLEN GRANULE STATE, AND FOR A TIME TO EFFECT THE DESIRED DEGREE OF ESTERIFICATION, THE PH OF THE SYSTEM BEING MAINTAINED AT LEAST ABOVE 9.0, THEREAFTER NEUTRALIZING THE SYTEM AND WASHING WITH WATER AND DRYING THE RESULTANT DISTARCH PHOSPHATE. 